Arrangement for a sensor and its wire connections in a mulitple-plate metal cylinder-head gasket

ABSTRACT

An arrangement for a multilayer cylinder head gasket comprising at least two plates, one lower and one upper, with ribs, a base plate and an intermediate plate containing a sensor disposed in the immediate vicinity of the edge of the cylinder orifice and wires for transmitting the information provided by the sensor, characterized in that it consists of accommodating a baffle between the base plate and the intermediate plate for the passage of the wires along the baffle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/EP2003/006922, filed Jun. 30, 2003. This application claims thebenefit of French patent application 0208527, filed Jul. 8, 2002. Thedisclosures of the above applications are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to the arrangement of a sensor and of itswire connections in a metallic multiplayer cylinder head gasket.

BACKGROUND OF THE INVENTION

Internal combustion engines are becoming more and more potent and moreand more controlled in terms of both the fabrication of the pieces thatconstitute them and their operation once they have been mounted andplaced into service.

As a result, combustion is an important aspect not only from thestandpoint of improving the efficiency and performance of these engines,but also from that of limiting pollution.

One arrives at this result by carefully determining the quantities offuel and combustion supporter, the torque, the point of introduction andthe circulation before and after explosion, by limiting the dead zones,by controlling with high accuracy the heights of the gasket and, inparticular, by controlling the explosion.

The fuels themselves have been improved.

A number of these parameters depend on the operating conditions of theengine, such as the external air temperature, the temperature of thefuel-air mixture before it enters the combustion chamber, the enginetemperature, the temperature of the exhaust gas, and all the engine loadparameters that depend on the vehicle load and the kind of driving.

Numerous sensors are available for measuring these parameters and fortransmitting them to a data acquisition and control unit by fibers or byindependent wires or through a bus.

These sensors are of a known type. They are disposed at different spotsof the engine and in places provided in the engine block and in thecylinder head to sense from the outside different fluid circuits.

On the other hand, what is not available are the parameters that aremost important to know, for example the temperature and pressure insidethe combustion chamber, nor are there any indications of theoscillations of the cylinder head compared to the engine block or of thevariations in sealing tightness or fatigue of the head cylinder gasketor of changes in its elasticity constants with time.

It is, however, precisely this area in which it is advantageous toaccurately measure all these parameters if one wants to ensure improvedand more accurate driving. This would tend toward an optimization of thecombustion cycle efficiency and reduced pollution by limiting the volumeof unburned exhaust substances. On the other hand, the problems lies inplacing one or more sensors in the immediate proximity of eachcombustion chamber of an internal combustion engine, namely in directcontact with the internal volume of the combustion chamber, knowing thatthe chamber must remain perfectly closed and that none of the sensorsmust cause a change in mechanical parameters and, in particular, mustnot require excessive thickness.

An attractive localization that makes it possible to meet theserequirements is in the cylinder head gasket. The cylinder head gasket isa perfect interface because of its placement relative to the combustionchamber.

Moreover, modification of the cylinder head gasket and the adaptation ofa sensor are not easy to do, but they can be done. In the case of theengine block, however, the difficulty is to achieve subsequently atightly sealed passage.

This is in fact where the greatest problem arises, because once a sensoris put in place it must be possible to connect it to the dataacquisition and control unit which necessarily requires the use of afiber or a wire.

SUMMARY OF THE INVENTION

The arrangement according to the present invention makes it possible touse the cylinder head gasket as the site for implanting at least onesensor regardless of the physical parameter measured, and it proposes asolution for the passage of fibers or wires.

In the following description, the term wire will be used to indicateindifferently a conductor based on an electric wire made of copperenveloped by a thermally and electrically insulating covering or one ormore optical fibers also enveloped by a thermally and electricallyinsulating covering or else a flat, flexible printed conductor.

In fact, to be able to connect the wire to the data acquisition andcontrol unit, it must be possible to make the wire pass through thecylinder head gasket of the combustion chamber all the way to theperiphery of the gasket.

To prevent the wire from being damaged, the wire must not be subjectedto pressures arising from the tightening of the cylinder head gasket andit must not interfere with the primary function of the gasket, namelyproviding a tight seal between the cylinder head and the engine block.

Patent applications are known in which attempts are made to find asolution to this problem, but these attempts have been unsatisfactory.

For example, in Japanese patent application JP-91958814, the cylinderhead gasket used is a multilayer gasket. A sensor is provided which isdisposed in the immediate proximity of the edge of the cylinder orifice.The wires themselves are disposed in a recess provided in the thicknessof a first plate of the gasket. A compressible material integral with asecond plate is superposed on this recess to keep the wires in theirplace.

U.S. Pat. No. 5,659,132 discloses a system of sensors that makes itpossible to measure the parameters in the combustion chamber, the signaloutput being measured outside the engine block. The cylinder head gasketis used to permit the passage of the connecting wires. The means usedconsist of a rigid tube having a diameter greater than that of theconductor or conductors lodged therein, the empty surrounding spacebeing filled with an insulating material. Such an arrangement issatisfactory but requires machining of the pieces that face each otherto form recesses capable of receiving each tube. This is expensive andrequires great precision incompatible with industrial fabrication inlarge series.

The arrangement according to the present invention will now be describedin detail for a preferred embodiment and its variants.

BRIEF DESCRIPTION OF THE DRAWINGS

This description refers to the attached drawings in which the differentfigures represent the following:

FIG. 1 shows a view in perspective of a part of the multilayer cylinderhead gasket with a sensor and a superposition of certain layers;

FIG. 2 shows an exploded view of elements constituting the part of themultilayer cylinder head gasket with a sensor of FIG. 1;

FIG. 3 shows a cross-sectional view of a part of the multilayer cylinderhead gasket with a sensor such as that shown in FIG. 1;

FIG. 4 shows a view in perspective of a variant of a part of themultilayer cylinder with a sensor and a superposition of certain layers;

FIG. 5 shows a cross-sectional view of the part of the gasket of FIG. 4;and

FIG. 6 shows an exploded view of different elements of the part of thegasket of FIGS. 4 and 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1 is represented a part of a cylinder head gasket 10 of themultilayer kind. The layers comprise two plates, namely a lower plate 12and an upper plate 14. In this case, each plate 12 and 14 is providedwith a rib 16 and 18, respectively. On a side of the cylinder orifice 20is provided a peripheral stopper 22 that is interposed between the lowerplate 12 and the upper plate 14.

The stopper 22 is made of a single piece 24, either in a foundry or bymachining, and is provided with a seat 28. The seat 28 can be obtainedby any means, such as casting, embossing, machining or stamping. Thetotal height results in a thickness E.

A sensor 30 is disposed in the seat and rests on or is integrated withthe lower plate 12. On one of its sides 32, the seat 28 isadvantageously open toward the cylinder orifice 20 and opens into thecombustion chamber. Thus, the sensor 30 can be in direct contact withthe environment prevailing in the chamber, which makes it possible tomeasure different parameters depending on the nature of the sensor 30.

Seat 28 also has a passage 34 for wires 36 that faces the open side 32.The wires 36 are connected to the sensor 30. The wires 36 comprise anextension possibly in a flat covering 38 which, for example, is moldedand which has a double-baffle cross-section. The cross-section can alsobe defined as being U-shaped with open branches 40 and a flat bottom 42.

The cylinder head gasket 10 of minimum configuration also comprises abase plate 44 to which is attached the stopper 22. The base plate 4 inthis first embodiment is preferably mounted in a floating fashion.

The base plate 44 has a window 46 opposite the wires 36 of the sensor30, and is aligned with the seat 28.

The dimensions of the window 46 are such that it is able to receive thedouble baffle of the branches 40 and the bottom 42. Thickness e1 of thebase plate 44 is greater than the thickness of the wires 36 includingtheir covering 38.

On the base plate 44 is disposed an inserted (intermediate) plate 48.The inserted plate 48 comprises a bridge 50 and two open windows 52 and54 that are disposed on the two sides of the bridge 50.

The two windows 52 and 54 are oriented so as to be above the wires 36 ofthe sensor 30 and more particularly its covering 38.

The bridge 50 is disposed so as to be above the flat bottom 42 whichallows the two branches 40 to extend on the two sides of the bridge 50.

A thickness e2 of the intermediate plate 48 is greater than thethickness of the wires 36 including their covering 38.

The sum of thickness e1 of the base plate 44 and thickness e2 of theintermediate plate 48 is less than the thickness E of the stopper 22.

Note that in the particular arrangement of the invention, represented incross-section in FIG. 3, the rib 16 of the lower plate 12 touches thebase plate 44 in a manner that blocks window 46, and that the rib 18 ofthe upper plate 14 touches the bridge 50.

It can be seen that with such an arrangement the wires 36 and theircovering 38, if any, pass through the double-baffle channel resultingfrom the geometry of the various pieces constituting the cylinder headgasket 10.

This arrangement does not interfere with tight sealing in the zone thatis of interest from the stand-point of the present invention, becausethe remainder of the gasket surface is subject the usual rules andassociated behavior.

In fact, it can be seen that the stopper 22 absorbs the tighteningstresses arising between engine block BM and the cylinder head CU. Thelower plate 12 and the upper plate 14 ensure a tight seal opposite thestopper 22 in the zone of the sensor 30. Preferably, a filling materialis added around the sensor 30 in the seat 28, on the one hand toimmobilize it and, on the other, to ensure that the first tightnessbarrier is as effective as possible.

As for the second tightness barrier, it is also provided opposite theribs 16 and 18. Thus, the rib 16 of the lower plate 12 presses againstthe base plate 44, and the rib 18 presses against the upper plate 14.

It can also be seen that the wires 36 are not subjected to compression.

To fill in the free volumes around the wires 36 and to ensure supportfor them, it is possible to intro-duce a polymer, preferably one of theheat-resistant elastomer type.

FIGS. 4, 5 and 6 show an embodiment wherein identical elements and thosehaving the same function bear the same reference numeral increased by100.

In this embodiment, the base plate 44 is a thick plate with the stopper122 integrated therewith, namely providing a monolithic assembly. Thebase plate 44 comprises a window 146 essentially identical to window 46except that the support edges for wires 136 with a covering 138 on thewindow 146 are beveled.

An intermediate plate 154 is a thin plate to ensure that the totalthickness is less than the thickness opposite the stopper 22, as in theprevious case. The thickness of the intermediate plate 154 isapproximately equal to that of the wires 136.

Opposite the double baffle, opposite flat bottom 142, the intermediateplate 154 comprises a projecting bridge 150, the profile of whichapproximately corresponds to that of the window 146 of the base plate44.

The mounting is identical to the previous one, and it is advantageous toadapt the profile of ribs 116 and 118 so as to ensure that the pressurestresses are properly applied to the lower and upper plate.

In this arrangement, as specifically shown in FIG. 4, with the assemblymounted, the wires with the passage along the baffle are not exposed toany risk of being crushed even in the long term because they do not comein contact with any element.

Tight sealing is respected, and the gasket can fulfill its primaryfunction between the engine block and the cylinder head.

Note that the industrial fabrication of such plates is made easier. Theproducts shown schematically in the figures must be adapted by thoseskilled in the art so that the complementary cutting is made immediatelyat the time of stamping of the completed layer even though thearrangement according to the invention does not require anysupplementary operation.

Note also that the objective of the present invention is attained,because the wires emerge from the cylinder head gasket into thethickness of which they are embedded thus transmitting the informationprovided by the sensor to a data acquisition and treatment unit, andthis without ever being subjected to compression that could createdegradations.

In the case where the wires are optical fibers, the radius of curvatureopposite the baffle is compatible with the authorized curvature radiiand does not disturb the information carried by said fibers. The edgesof the various windows and seats can be beveled or flared out dependingon the need.

1. An arrangement of a multilayer cylinder head gasket comprising: anupper plate and a lower plate, each plate including a pair of; a baseplate; an intermediate plate comprising a sensor disposed in animmediate vicinity of an edge of a cylinder orifice; and wires fortransmitting information provided by the sensor, wherein a baffle isdisposed between the base plate and the intermediate plate for thepassage of the wires along the baffle.
 2. The arrangement of amultilayer cylinder head gasket according to claim 1, wherein the baseplate comprises a window opposite the wires of the sensor, and theintermediate plate comprises a bridge and two open windows disposed oneach side of the bridge
 3. The arrangement of a multilayer cylinder headgasket according to claim 2, wherein the bridge is disposed so as toposition itself above the wires passing along the baffle with a flatbottom and two branches.
 4. The arrangement of a multilayer cylinderhead gasket according to claim 3, wherein a thickness of theintermediate plate is greater than a thickness of the wires, and thebridge is in a plane of the intermediate plate.
 5. The arrangement of amultilayer cylinder head gasket according to claim 3, wherein thethickness of the intermediate plate is approximately equal to athickness of the wires, and the bridge forms a projection in the windowof the base plate.
 6. The arrangement of a multilayer cylinder headgasket according to claim 1, further comprising a stopper disposedbetween the ribs of the upper and lower plates and opposite the baseplate and the intermediate plate, wherein a height E of the stopper isgreater than a sum of a heights e1 of the base plate and a height e2 ofthe intermediate plate.
 7. The arrangement of a multilayer cylinder headgasket according to claim 6, wherein the stopper comprises a seat forreceiving the sensor, the seat being open on one side toward thecylinder orifice and comprising a passage.
 8. The arrangement of amultilayer cylinder head gasket according to claim 7, wherein aplurality of free spaces around the sensor in the seat are filled. 9.The arrangement of a multilayer cylinder head gasket according to claim6, wherein the stopper is mounted so as to float relative to the upperand lower plates.